There has been typically used a buckle that detachably engages a plug with a socket in order to couple string members (e.g., belts) in various applications (e.g., clothes, bags, shoes and packages).
Such a buckle requires easy handling for coupling and releasing as well as no accidental release when the buckle is not intended to be released. As a product that satisfies such needs, a side release buckle including a pair of lock arm on both sides thereof has been used.
For instance, a side release buckle disclosed in Patent Literature 1 or 2 includes a plug and a socket, each of which is provided with a belt attachment.
The plug includes a base including the belt attachment and a pair of legs (lock arms) on both sides near the socket. The socket includes a hollow cylindrical body, the body having a housing space (cavity) into which the plug is inserted from a plug-facing side of the body. An opening in communication with the housing space is formed on each side of the body of the socket. The plug and the socket can be disengaged by manipulating the legs exposed through the openings with fingers.
Among the above side release buckles, the side release buckle disclosed in Patent Literature 1 includes a prismatic guide bar between a pair of legs of the plug in order to stabilize a posture of the plug when the plug is inserted into the socket.
On the other hand, in the side release buckle disclosed in Patent Literature 2, a guiding function of a pair of legs is enhanced, whereby a guide bar is omitted. However, the side release buckle disclosed in Patent Literature 2 additionally includes a connecting belt configured to connect the pair of legs. The connecting belt, which is a member shaped in a thin plate, is integrally formed with the legs and the like. The connecting belt connects the pair of legs while being curved in a substantially U-shape. The connecting belt is configured to suppress excessively outward deformation of the legs to prevent breakage thereof.